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LOSETUP(8)                   System Administration                  LOSETUP(8)

NAME
       losetup - set up and control loop devices
SYNOPSIS
       Get info:
            losetup loopdev
            losetup -l [-a]
            losetup -j file [-o offset]
       Delete loop:
            losetup -d loopdev...
       Delete all used loop devices:
            losetup -D
       Print name of first unused loop device:
            losetup -f
       Set up a loop device:
            losetup [-o offset] [--sizelimit size]
                    [-Pr] [--show] -f|loopdev file
       Resize loop device:
            losetup -c loopdev
DESCRIPTION
       losetup  is  used to associate loop devices with regular files or block
       devices, to detach loop devices and to  query  the  status  of  a  loop
       device. If only the loopdev argument is given, the status of the corre-
       sponding loop device is shown.
       Note that the old output format (e.g. losetup -a) with comma  delimited
       strings  is deprecated in favour of the --list output format (e.g. los-
       etup -a -l).
OPTIONS
       +The size and offset arguments may be followed  by  the  multiplicative
       +suffixes  KiB=1024,  MiB=1024*1024,  and so on for GiB, TiB, PiB, EiB,
       ZiB and YiB +(the "iB" is optional, e.g. "K" has the  same  meaning  as
       "KiB")  or  the  suffixes +KB=1000, MB=1000*1000, and so on for GB, TB,
       PB, EB, ZB and YB.

       -a, --all
              show status of all loop devices. Note that not  all  information
              are accessible for non-root users. See also --list. The old out-
              put format (as printed without --list) is deprecated.
       -c, --set-capacity loopdev
              force loop driver to reread size of the file associated with the
              specified loop device
       -d, --detach loopdev...
              detach  the  file  or  device associated with the specified loop
              device(s). Note that since Linux v3.7 kernel uses  "lazy  device
              destruction".   The detach operation does not return EBUSY error
              anymore if device is actively used by system, but it  is  marked
              by autoclear flag and destroyed later.
       -D, --detach-all
              detach all associated loop devices
       -f, --find
              find  the  first  unused  loop  device.  If  a  file argument is
              present, use this device. Otherwise, print its name
       -h, --help
              print help
       -j, --associated file
              show status of all loop devices associated with given file
       -l, --list
              if a loop device or the -a option is  specified,  print  default
              columns  for  either  the  specified  loop  device  or  all loop
              devices, default is to print info about all devices.
       -o, --offset offset
              the data start is moved offset bytes into the specified file  or
              device
       -O, --output columns
              specify which columns are to be printed for the --list output
       --sizelimit size
              the  data  end  is set to no more than size bytes after the data
              start
       -P, --partscan
              force kernel to scan  partition  table  on  newly  created  loop
              device
       -r, --read-only
              setup read-only loop device
       --show print  device  name  if  the  -f  option and a file argument are
              present.
       -v, --verbose
              verbose mode

ENCRYPTION
       Cryptoloop is no longer  supported  in  favor  of  dm-crypt.  For  more
       details see cryptsetup(8).

RETURN VALUE
       losetup returns 0 on success, nonzero on failure. When losetup displays
       the status of a loop device, it returns 1 if the device is not  config-
       ured  and  2  if an error occurred which prevented from determining the
       status of the device.

FILES
       /dev/loop[0..N]
              loop block devices
       /dev/loop-cotrol
              loop control device

EXAMPLE
       The following commands can be used as an  example  of  using  the  loop
       device.
              # dd if=/dev/zero of=~/file.img bs=1MiB count=10
              # losetup --find --show ~/file.img
              /dev/loop0
              # mkfs -t ext2 /dev/loop0
              # mount /dev/loop0 /mnt
               ...
              # umount /dev/loop0
              # losetup --detach /dev/loop0
AUTHORS
       Karel  Zak  <kzak AT redhat.com>,  based on original version from Theodore
       Ts'o <tytso AT athena.edu>
AVAILABILITY
       The losetup command is part of the util-linux package and is  available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

util-linux                         July 2003                        LOSETUP(8)